Think Agronomy: Prepare For Locust Plague

Think Agronomy: Prepare For Locust Plague

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Farmers of every crop type including livestock are being urgent to make plans to deal with the potential locust plague that spread from Somalia across Wajir, and has already devoured tens of thousands of acres around Marsabit.

Co-ordinated approach or not, there are steps individual farmers can take to reduce the risk to their own crops, including having the right insecticides in store ready to apply BEFORE the pests hits. Some products have a persistence of up to a week even at Ultra Low Volume, so given the speed that the swarms have moved already, it would be wise to be pre-empting their arrival at any time. 

locust invasion outbreak 2019 2020
Map showing regions affected by the recent locust plague

A spray application over as much of the shamba as is practically possible, either with a tractor sprayer or an aeroplane, will buy valuable time, and better to be a week early than a day late. Contact our crop consulting team for specific independent advice on products, rates and application techniques. 

Soil Testing Saves 1,870 Ksh/ha on Seedbed Fertilizer Costs

Whilst many soils in Kenya tend to be very low in Phosphate, most farms have a field or two which have higher P levels, perhaps from historical livestock bomas or different soil types. Carrying out a soil test allows you to identify these areas and potentially make savings in fertilizer costs without sacrificing yields. 

One such client last year moved from a flat rate of 125kg/ha DAP, to an average of 91kg/ha DAP and some 23.23.0 by adjusting planting fertilizer rates according to P levels. This reduced the seedbed fertilizer cost from 6,875 Ksh per hectare to 5,005 Ksh, leading to savings of 1,870 Ksh per hectare.

The majority of fields on the farm had P levels around 5ppm, however several fields were found with well over 30ppm, and in one case 75ppm of P.

soil testing
One of the Cropnuts P response trials. Nitrogen is equalled across all treatments so that the optimum rate of P can be observed at harvest

Our seedbed fertilizer trials in the area on similar soil types – looking at responses to different rates of P – have been conducted on a range of sites with P levels ranging from 5 to 30ppm, giving the confidence to reduce rates gradually when soil levels reach 30 ppm, and to cut rates down to just 20kg/ha of phosphate in many high P situations.

It is crucial not under fertilize in the name of cost saving, however having a network of trials and experience from our Agronomy Client’s farms, we have the confidence to identify the situations where savings can be made without detriment to yield.

The foundation for this is a good, accurate soil test that represents the true picture within the field, remembering that areas of which have a different soil type or history should be sampled separately.

How Do I Get A Soil Test Service?

  1. Get in touch with us and our field staff will collect soil test samples from each field and appropriate areas within each field.
  2. Our field staff will send the samples to our laboratory along with the planned crop to be planted.
  3. Receive a tailored soil test recommendation for each field with the type and rate of fertilizer, lime and foliar micronutrients required.

Want To Go A Step Further?..Sign Up For Our Precision Farming Service

  1. Within-field variation opens up huge possibilities for optimizing nutrition and raising yields for farmers with satellite technology such as Global Positioning System (GPS) and Variable Rate Technology. (Sign up your farm for free satellite imagery here)
  2. Sampling each field on a 1 hectare of 5 hectare grid allows a map to be produced and fertilizer rates to be allocated to different P levels.
  3. A rate controller on the planter allows seedbed fertilizer to be changed on the move, saving money (and reducing lodging) in strong areas, and giving the crop the optimum in poorer areas.
  4. Try and apply a small strip of half rate and double rate application in each field as a way of visually checking the crop’s requirement of any nutrient.

Potato Blight Explosion

Blight pressure has been extremely high during the recent wet weather, and keeping on top of the disease is a must to avoid yield loss and problems in store.

Keeping the spray interval close is crucial – 4-5 days max between blight fungicides in order to protect new growth when there are disease lesions actively sporulating in the crop. This can require 10-12 fungicides in some crops, and many growers question what product to use once they have been through their tried and trusted fungicides. But fear not…

Potato blight
Prospects for potato crops look good provided Blight can be kept at bay. Even in severe case where the crop is heavily defoliating with disease, do not give up. Tuber initiation in most crops is excellent so will still reward those who persevere. Right side picture showing potato crop severely affected by blight in Meru County, Kenya

The labels of Revus (mandipropamid), Orvego (ametoctradin + dimethomorph) and the eagerly awaited Zorvec all permit three consecutive applications, and are different modes of action. This immediately gets you nine consecutive treatments!

Add in propamocarb products (e.g. Infinito) which in most countries has a limit of four applications but no maximum consecutive number and you can see that season-long protection can at least be kept simple.

Benthiavalicarb is now approved in Kenya too which is excellent news, however this is from the same group as Orvego so should NOT be used consecutively, for resistance management.

Remember too that multi-site inhibitors such as mancozeb play a major part in resistance management, and are in fact a label requirement in products such as manipropamid many countries. Cymoxanil also gives some curative activity in high pressure situations and is fairly inexpensive.

Towards the end of the program fluazinam still works very well on tuber blight, and fluazinam-insensitive blight strains – first identified in 2017 – actually declined in Europe this year.

And finally, reduce blight pressure by controlling volunteer potatoes. We have been busy spraying and uprooting volunteers around our trials this week to avoid them spreading blight spores to nearby crops.


Farming for the future requires a change of approach. Monoculture, soil degradation and climate change and soil degradation are threats to the future of how we feed the planet. Agventure Ltd set up the Center of Excellence for Crop Rotation to help farmers diversify cropping systems and introduce techniques which have a long-term outlook to improve soil health. The Center of Excellence for Crop Rotation works extensively with Crop Nutrition Laboratory Services Ltd (Cropnuts).

About David

David Jones is the Broad Acre Specialist at Crop Nutrition Laboratory Services Ltd. (CROPNUTS). David has a keen interest in soils and no till farming systems where he has undertaken work looking into weed levels and changes in soil structure, and has extensive experience in field trials and in the development of precision farming techniques. In his spare time he enjoys playing rugby.

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